Changes In Equity And Comprehensive Income (Summary Of Changes In Equity) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 1,145.7	$ 1,150.8
Dividends	(19.6)	(19.2)
Exercise of stock options, net of shares reacquired	12.8	(1.4)
Stock compensation expense	5.6	6.1
Excess tax benefit from stock based compensation	0.0	(0.3)
Net income	63.3	55.2
Other comprehensive income (loss)	24.5	33.7
Comprehensive income	87.8	88.9
Balance, end of period	1,232.3	1,224.9
Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	1,133.8	1,139.4
Dividends	(19.6)	(19.2)
Exercise of stock options, net of shares reacquired	12.8	(1.4)
Stock compensation expense	5.6	6.1
Excess tax benefit from stock based compensation	0.0	(0.3)
Net income	63.1	55.0
Other comprehensive income (loss)	24.3	33.6
Comprehensive income	87.4	88.6
Balance, end of period	1,220.0	1,213.2
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	11.9	11.4
Net income	0.2	0.2
Other comprehensive income (loss)	0.2	0.1
Comprehensive income		0.3
Balance, end of period	$ 12.3	$ 11.7